How to check if a value in one list is in another list with a one-liner for an if statement in Python if I'm not using sets?

Question

I\'m trying to construct a one liner that would check if any of the values in one list are present in another list and return True or False if it does or does not.

T

Answer 1

You could also do

set(list1).intersection(list2)

to get the set of elements that occur in both; the length of the set is 0 if there's no intersection, otherwise positive. You can treat this set as a boolean, since Python evaluates empty sets to False and nonempty sets to True.

if set(list1).intersection(list2):
    print ('Lists have elements in common')
else: 
    print ('No elements in common')

Runtime is O(n) average-case, O(n^2) worst-case: https://wiki.python.org/moin/TimeComplexity